Step stool



FIG. 1 is a front perspective view of a step stool embodying my new design.

FIG. 2 is a bottom plan view thereof.

FIG. 3 is a top plan view thereof.

FIG. 4 is a rear elevational view thereof.

FIG. 5 is a front elevational view thereof.

FIG. 6 is a right side elevational view thereof; the opposite side being a mirror image. 

The ornamental design for a step stool, as shown and described. 